Thursday, June 28, 2018

The 7 Weirdest Aphid Behaviors

Not much to look, at but a devil to deal with in the garden – aphids are fascinating and unique creatures of the insect kingdom. In my humble opinion they deserve respect. Here are some interesting factoids about the nefarious aphid:

1. Is That Blue Bug Really an Aphid? 

Most commonly aphids are an off-white, cream color but don’t be fooled – if it looks like an aphid and eats the sugars out of the bottom of leaves like an aphid – it is an aphid. They come in virtually all colors: blueish-black, purple, pink, yellow and green. The way to identify them is to look at the underside of leaves with mottled yellow spots showing up. They cluster underneath leaves so it is critical when treating to get any sprays under the leaves and on top of the leaves.

2. Their Tailpipes Produce More Than Exhaust

The aphid has tailpipes called cornicles (or siphunculi) that produce a waxy fluid (cornicle wax) used for self-defense from predators and parasites. When attacked, aphids produce the cornicle wax to deter predators and trap parasitoid insects. It’s a bit like dropping the banana peel in the path of pursuers in the game Mario Kart. 

3. They Produce Double Duty Pheromones

While most insects are satisfied with pheromones that only help with the mating process, aphids have adapted to produce pheromones that also alert their compadres to insect threats. Once an aphid releases the alarm pheromone, the aphid colony rapidly moves en masse to another location. The colony may lose a few, but the majority will survive.  Always one step ahead of the game – ladybugs have adapted to locate this pheromone source to have a nice meal. 

4. Aphids Poop Sugar…and Lots of It 

One of the ways to identify an aphid infestation is if you find a thin, sticky substance on the plant leaves. Upon further investigation of the underside of the leaves you will most likely locate a colony of aphids. Aphids suck the sugars from plant foliage creating pinpoint mottled yellow spots on the leaves they are feeding on. 

The sugar or leaf sap is high in sugar and the aphids can’t use it all. So, the overflow is channeled out through two pipes, each adjacent to the anus. This sticky stuff is called honeydew and they leave it behind to make room for more – because their job is to remove this life source from your plant.

The honeydew attracts ants and fungal diseases – one of which is a black sooty mold that develops on the leaves. I’ve found that a spray of Neem oil helps to control the aphids AND clean off the honeydew and sooty mold from the leaves. Sometimes if we let the honeydew and aphid situation go long enough, ladybugs will pick up on the pheromone scent and sweep in to clear out the infestation, but conditions need to be right for ladybugs to show up. You will still be left with cleaning up the honeydew, so keep that Neem Oil handy. 

5. Aphids Reproduce Asexually

There is some life cycle variation among aphid species, but the basics remain the same. Eggs are laid in the fall and hatch in spring. This generation are wingless females that reproduce asexually by a process called parthenogenesis. This process occurs when the ovum develops without fertilization. These early generations are followed in the same season by winged females who produce a generation of females and males that reproduce sexually. The parthenogenic adaptation allows the colonies to be less dependent upon males. 

6. To Wing or Not to Wing?

In addition to the winged generation of females referenced above, the wingless aphids can produce wings as needed. This is related to preservation of the colony. If plants become too crowded or the environmental conditions become adverse, some or all of the aphids will develop wings and use the local winds to relocate to a more suitable location.  

7. Social Aphids and the Tragedy of the Commons

The social species of aphids are all gall making. Examples of these aphids are wooly apple aphids, eastern spruce gall aphids and the green peach aphid. They produce the galls by secreting long strands of a wax material that forms a wooly coating for their colonies.The aphids live in the galls that form as the plant reacts to the secretion. These communities are dense and clonal. Within these colonies, nymphal soldiers are produced to protect the colony from predators and other aphid colonies. These clone colonies work together to protect and maintain the colony. However, “cheaters” or interlopers from other colonies may try to join the colony and disrupt the balance of the colony. When this occurs, the entire population ignores the ongoing needs of the colony and they feed very quickly and negatively impact the native (original) population. This ruins the party. These cheaters upset the balance of the colony leading to resource (food) scarcity. 

What To Do About Aphids?

No matter whether you fear the aphid or revere it, remember that you can easily control them by:
  • Limiting the amount of nitrogen you apply to the soil.
  • Use sticky traps to trap and monitor and reduce reproduction.
  • Use sharp shots of water to reduce populations.
  • Keep some Neem Oil around to use for both aphid control and cleaning off the honeydew. 
  • Encourage or supplement populations of ladybugs and green lacewing – the natural predators of the aphid.
  • Like most other garden pests, control is always easiest when action is taken early in the season. Make sure you do your due diligence and you’ll be well on your way to an aphid-growing season.  

-Contributed by Deb at ARBICO Organics


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